pg11b1 from outside a txn: "VACUUM cannot run inside a transactionblock": should be: ...or multi-command string

in pg10:

    ts=# begin;VACUUM FULL pg_toast.pg_toast_2619;
    BEGIN
    ERROR:  25001: VACUUM cannot run inside a transaction block
    LOCATION:  PreventTransactionChain, xact.c:3167
=> sounds fine

    $ psql postgres -c 'SELECT 1; VACUUM pg_statistic'
    ERROR:  VACUUM cannot be executed from a function or multi-command string
=> sounds fine

In pg11b1:

    pryzbyj=# begin;VACUUM FULL pg_toast.pg_toast_2619;
    BEGIN
    ERROR:  25001: VACUUM cannot run inside a transaction block
    LOCATION:  PreventInTransactionBlock, xact.c:3163
=> sounds fine

    [pryzbyj@dev ~]$ psql -c 'SELECT 1; VACUUM pg_statistic'
    ERROR:  VACUUM cannot run inside a transaction block
=> Error message seems off??

I couldn't figure out how to \set VERBOSITY verbose inside a psql command (??),
but strace shows for v10:
SERROR\0VERROR\0C25001\0MVACUUM cannot be executed from a function or multi-command
string\0Fxact.c\0L3187\0RPreventTransactionChain

And for v11:
SERROR\0VERROR\0C25001\0MVACUUM cannot run inside a transaction block\0Fxact.c\0L3163\0RPreventInTransactionBlock

Function renamed by commit 04700b685f31508036456bea4d92533e5ceee9d6.

So behavior change maybe caused by 6eb52da3948dc8bc7c8a61cbacac14823b670c58 ?

Justin